Image forming apparatus featuring a variable oscillating electric field formed between a developer carrying member and an image bearing member during a developer operation in accordance with a peripheral speed of the image bearing member

An image forming apparatus comprising:

• an image bearing member;
• and
• a developer carrying member, disposed opposed to said image bearing member, for carrying a developer,
• wherein an electric field is formed between said developer carrying member and said image bearing member during a developing operation using said developer carrying member, and the electric field includes an oscillating portion in which the electric field is an oscillating electric field, and
• wherein a supply electric field of said oscillating electric field which is effective to supply the developer to said image bearing member from said developer carrying member is variably controllable in accordance with a peripheral speed of said developer carrying member.

An image forming apparatus comprising:

• an image bearing member;
• and
• a developer carrying member, disposed opposed to said image bearing member, for carrying a developer,
• wherein an electric field is formed between said developer carrying member and said image bearing member during a developing operation using said developer carrying member, and the electric field includes an oscillating portion in which the electric field is an oscillating electric field, and a non-oscillating portion in which the electric field is a non-oscillating electric field, which appear alternately, and
• wherein a percentage of a time duration of the oscillating portion during the developing operation is variably controlled in accordance with a peripheral speed of the image bearing member.